1. Field of the Invention
The present invention relates to a recording medium, such as an optical disk, for recording compressed moving picture data, audio data and the like or different kinds of data, an apparatus and method of recording data on this recording medium, and an apparatus and method of reproducing data from the same.
2. Description of the Related Art
Recently, optical disk players, which can handle moving pictures and play optical disks on which picture and audio data are digitally recorded, have been developed, and are widely used as players for movie software, karaoke and so forth. Further, MPEG (Moving Picture Image Coding Expert Group) standards have recently become international standards for a data compression system for moving pictures. This MPEG system performs variable length compression of picture data.
The MPEG2 system is now also being internationally standardized, so that the system format which matches with the MPEG compression system is defined as an MPEG2 system layer. This MPEG2 system layer defines the setting of a transfer start time and a playback start time, expressed by using a reference time, in moving picture data, audio data and other data, so that those data can be transferred and reproduced synchronously. Playback is normally executed using this information.
With the increasing availability of optical disks designed for multiple uses, it is not sufficient to consider only the synchronism among individual pieces of data.
For educational purposes, such as learning languages, for example, main picture data used as video data may present questions to users, while sub-picture data superimposed on the picture may give answers to the users. In this case, it is significant to show answers after, and not before or during the time questions are given.